Heat treatment of materials for distilling, drying, or carbonizing them



March 13, 1928. 1,662,663

A. MOD. DUCKHAM ET AL HEAT TREATMENT OF MATERIALS FOR DISTILIJING, DRYING, OR CARBONIZING THEM Filed Jan. 12, 1925 3 Sheets-Sheet, 1

March 13 1928 1,662,663

v A. M D. DUCKHAM ET AL HEAT TREATMENT OF MATERIALS FOR DISTILLING, DRYING, OR CARBONIZING THEM Filed Jan. 12, 1925 5 Sheets-Sheet 2 l I I March 13, 1928. T 1,662,663

A. M D. DUCKHAM ET AL HEAT TREATMENT OF MATERIALS FOR DISTILLING, DRYING, OR CARBONIZING THEM Filed Jan. 12. 1925 s Sheets-Sheet 5 Patented Mar. 13, 1928.

,. UNITED STATES PATENT OFFICE.

anrnua ucnoucnn DUCKHAM, DOUGLAS RIDER, AND JOHN smxms warms, or LONDON, ENGLAND.

1 HEAT TREATMENT OF MATERIALS FOB DISTILLING, DRYING, OR CARBONIZING THEM.

Application filed Jan-nary 12, 1925, Serial No.

This invention relates .to the heat treatment of materials for distilling, drying or carbonizing them.

In processes of continuous heat treatment 5 of a material by causing it to travel through an externally heatednetortor the like, the stirring action of the device which causes the travel, such as an Archimedean screw or two such screws in gear with each other,

plays an important part in causing particles which have become heated'by contact with the walls of the retort to mix with particles not so heated, so that the whole mass ultimately becomes heated. This mode of conveying the heat is very slow unless a considerable overheating of the particles that come into contact with the wall is permissible.

In cases where overheating is expressly 0 avoided byfthe known expedient of surmetal kept at a substantially constant temperature near-to that at which the heat treatment is to be conducted, the excess heat carried by the particles which have been in contact with the wall is so small that either the rate of travel must be very slow or much of the material must remain underheated.

The object of the present invention is an improved apparatus in which it is possible to conduct the heat treatment ofa subdi vided solid material insuch a manner that the material does not ack to ether and form a mass through which it is iflicult for heat to betransmitted and from which it is difficult to remove the gaseous products of the treatment sufiiciently rapidly to ensure that they are not exposed to prolonged action of high temperatures, and in such a manner that each iece or particle of the material may be raised to the required temperature in as. nearly as possible the same tlme.

In apparatus according to the invention, the material is spread in the form of a thin layer, and is caused totravel through a hot zone between 'two relatively moving solid surfaces, the material of the layer being continually turned over during the travel so as to bring practically all particles into contact with the heated boundary of the zone.

A suitable apparatus according to the invention comprises a horizontal externallyheated trough-shaped vessel containing a rotating horizontal cylindrical surface; the

rounding the retort or the like with molten 2,011, and in Great Britain January 17, 1924.

lower inner part of the vessel is substantially part-cylindrical, and the cylindrical surface is so positioned that its periphery is in close proximity to the part-cylindrical portion of the inner surface of the vessel. Material is caused to travel in the axial direction of the cylinder through the narrow part-annular space thus formed between the vessel and the cylindrical surface, and is turned over continually during the travel. By reason of the fact that only the lower, part-cylindrical portion of the vessel conforms to the shape of the rotating cylindrical surface there is in the upper part of the retort a relatively large space which facilitates the disengagement from the material of vapours evolved during the treat-' ment, and their rapid removal from the zones of higher temperature. By' reason of this construction, also, the vapours can gain this space without having to pass through any considerable thickness of heated material.

The device which turns over the material also causes its travel and consists of a screw thread carried on the cylinder and extending between the cylinder and the part-cylindrical plortion of the inner surface of the vessel.

aterial is prevented from adhering to the threaded cylindrical surface, which constitutes a conveying screw, by means of a scraping screw intermeshing with the conveying screw. Preferably, the thread of the scraping screw is of different hand from that of the conveying screw, that is'to say, one is left hand and the other right hand. The conveying screw causes the material to travel in the form of a thread of small cross section the particles in which are continually turned over by the action of the screw 9 or scraping screw. The latter also has a grinding action which breaks up coarse material or aggregates which may form as a result of the heating.

It is advantageous that the scraping screw should revolve at a less rapid peripheral speed than that of the conveying screw and the mode of attaining this object is to make the scraping screw of smaller diameter than the conveying screw and to rotate their axles at the same speed. This construction economizes space within the vessel.

Solid material is preferaol fed into the trough orretort in a finely su divided state. The invention is particularly applicable for the known method. of subjecting coal which is to be coked to a preliminary low temperature carbonization; also for the destructive distillation of shale and for the distillation of tar and oil until a coke residue is obtained.

In the accompanying drawings, Figs. 1 and 1 are a longitudinal section and Big. 2 is a cross section through an apparatus constructed in accordance with the invention.

A trough shaped retort a is set in a correspondingly shaped bath 1) containing lead which is kept at the required temperature above its melting point by the oil-fired furnace c. The shaft d is mounted at one end in a bearing 0 within the retort and at the other end in a bearing f carried by the end of the retort. On it is fixed a left hand screw-threaded cylinder 9 which is in mesh with a right hand screw it of similar pitch and carried by a shaft 2' mounted in the same manner as the shaft d. The latter shaft is driven by the gear is and drives shaft 6 through gear Z.

The material to be heated, such as pulverized shale, is fed into the retort through the hop er m and is conveyed by the screwthreaded cylinder 9 towards the other end of the retort where it is discharged into the chute n. This chute is closed at bottom by an arc-shaped tray '1' containing water to seal the chute and carried by arms 0, 0 on pivots p. Periodically the lever g forming an extension of arm 0 is operated to swing open the door constituted by the tray 1" so as to dump the carbonized shale which has collected on the tray. The volatile roducts of the carbonization escape throng the pipe connection 8.

Owing to the small depth of the screw thread on cylinder g the layer of shale powder which travels in contact with the heated wall of the retort is thin and becomes heated throughout. Any particles which adhere to the screw thread are scraped off and if necessary crushed by the screw h.

We claim- 1. Apparatus for the continuous distillation of a subdivided solid material, com rising a horizontal trough-shaped vessel a apted to be heated, and having its lower portion substantially part-cylindrical, a cylinder mounted to rotate in said vessel on a horizontal axis'parallel to the longitudinal axis of said vessel, with part of its periphery in close proximity to said part-cylindrical portion of the inner surface of the vessel, a screw thread carried by the cylinder and extending between the said cylinder and said portion of the inner surface of the vessel, means for feeding material to said thread, a scraping screw of diameter less than that of said cylinder, said screw having a thread intermeshing with and of hand different from the thread carried by the cylinder and adapted to remove material adhering thereto, and means for continuously rotating the said cylinder, and the said scraping screw with the same angular velocity in directions which are opposite in sense.

2. Apparatus for the continuous distillation of asubdivided solid material, comprising a horizontal trough-shaped vessel having its lower portion substantially part cylindrical, a cylinder mounted to rotate in said vessel on a horizontal axis parallel to the longitudinal axis of said vessel with part of its periphery in close proximity to said part-cylindrical portion of the inner surface of the vessel, an outer jacket surrounding at least the lower portion of said vessel and adapted to contain molten metal, a screw thread carried by the cylinder and extending between the said cylinder and said portion of the inner surface of the vessel, means for feeding material to said thread, a scraping screw of diameter less than that of the said cylinder, said screw having a thread intermeshing with and of hand different from the thread carried by the cylinder and adapted to remove material adhering thereto. and means for continuously rotating the said cylinder and said scraping screw with the same angular velocity in directions which are opposite in sense.

In testimony whereof we have signed our names to this specification.

ARTHUR McDOUGALL DUCKHAM.

DOUGLAS RIDER. JOHN saunas WATTS. 

